Hard disk drive device

ABSTRACT

The object of tho present invention is to provide a hard disk drive device having a bearing means of larger size and sufficient strength, improved impact resistance, high accuracy of rotation, and high reliabililty  
     In accordance with the present invention, a hard disk drive device is provided with a motor including; a rotor or hub having around outer periphery thereof a downwardly depending flange, said hub is journalled rotatablly on a base by means of a bearing means, maid hub is provided with a magnet on the inner peripheral surface of the downwardly depending flange, the hub is also provided with an inner shoulder on the top thereof; and a stator provided on the base so as to opposed face to face with said magnet, said stator includes coils: and a magnetic disk having a central aperture to be fitted around the inner shoulder provided on the hub: wherein the outer diameter of the downwardly depending flange of said hub is larger than the inner diameter of the central aperture of the magnetic disk, the outer diameter of said magnet surrounded by said downwardly depending flange ia larger than the outer diameter of said inner shoulder, the inner diameter of the magnet as well as the outer and inner diameters of the stator are enlarged, and the outer diameter of the bearing means is enlarged.

BACKGROUND OF THE INVENTION

[0001] 1. Technica1 Field

[0002] The present invention relates to an improvement of the hard diskdrive device employed for example in computers for storing datummagnetically.

[0003] 2. Description of the Prior Art

[0004] A hard disk drive device of the prior art as shown in FIG. 5includes a shaft 43 supported on a base 41 by means of bearing means 42.A rotor or hub 44 is fitted securely around the shaft 43. A magnet 46 isprovided on the inner surface of the flange 45 depending downwardly fromthe outer periphery of the hub. A stator 47 having coils 51 is connectedto the base so as to opposed face to face with the inner surface of themagnet.

[0005] A magnetic disk 48 is mounted on the outer peripheral portion ofthe hub 44. The oscillation of the disk is adapted to be inhibited by adisk restraining plate 52. Reading and writing of the magnetic datumfrom the given sector of the magnetic disk 48 is effected by themagnetic head 50 provided at the distal end of the head arm 49.

[0006] In recent years, it is desired to provide a smaller, thinner, andlighter weight, as well as impact resistant magnetic storage means,especially a hard disk drive device.

[0007] When impact is applied to the hard disk drive means, the impactenergy is apt to concentrated to the bearing means 42 journalling therotor or hub 44 of the motor for driving the magnetic disk, so that thebearing means is the element most liable to be damaged.

[0008] When the bearing means is damaged, the accuracy of the rotationof the magnetic disk 48 will be suffered, and the reading and writing ofthe magnetic datum can not be accomplished accurately, and noise andvibration are produced.

[0009] One of the counter measures which can be taken for preventing thedamaging of the bearing means is to strengthen the bearing means itself.This countermeasure is confronted with the problem that the magneticdisk 48 is standardized to have an outer diameter of 2.5 inch or 3.5inch, and the central aperture thereof is also standardized to have aninner diameter D₀ of 20.0 mm or 25.0 mm respectively.

[0010] In other words, the outer diameter of the hub as well as that ofthe magnet 46 and/or then stator 47 is adapted to be defined inaccordance with the diameter of the central aperture of the magneticdisk, so that the bearing means 42 of sufficient size and strength cannot be used.

[0011] Although the countermeasure that reducing the thickness of saidmagnet 46 or the radial length of the stator 47 to provide a spacerequired for enlarging the bearing means can be taken, this will sufferthe function of the motor such as the rotational torque or therotational speed. In this connection, this countermeasure can not beadopted,

[0012] Accordingly, the object of the present invention is to provide ahard disk drive device having a bearing means of larger size andsufficient strength, improved impact resistance, high accuracy ofrotation, and high reliability.

SUMMARY OF THE INVENTION

[0013] These and other objects are achieved by a hard disk drive devicecomprising a motor including a rotor or hub and a stator, and a magneticdisk. The hub has a flange depending downwardly from the outer peripherythereof. The hub is journalled rotatablly on a base by means of abearing means. The hub is provided with a magnet on the inner peripheralsurface of the downwardly depending flange. The hub is also providedwith an inner shoulder on the top thereof. The stator is provided on thebase so as to opposed face to face with said magnet. The stator includescoils. The magnetic disk has a central aperture to be fitted around theinner shoulder provided on the hub. The outer diameter of the downwardlydepending flange of said hub is larger than the inner diameter of thecentral aperture of the magnetic disk. The outer diameter of said magnetsurrounded by said downwardly depending flange is larger than the outerdiameter of said inner shoulder. The inner diameter of the magnet andthe outer and inner diameters of the stator are enlarged, and the outerdiameter of the bearing means is also enlarged

[0014] Further, in accordance with the present invention, the hub alsoincludes an outer shoulder larger in its diameter than that of the innershoulder and smaller than that of the downwardly depending flange.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Further feature of the present invention will become apparent tothose skilled in the art to which the present invention relates fromreading the following specification with reference to the accompanyingdrawings, in which:

[0016]FIG. 1 is a perspective view of the hard disk drive device of thepresent invention.

[0017]FIG. 2 is a longitudinal cross-sectional view of the hard diskdrive device of the first embodiment of the present invention.

[0018]FIG. 3 is an enlarged longitudinal sectional view of thesubstantial part of the hard disk drive device of the first embodimentof the present invention.

[0019]FIG. 4 is a longitudinal cross-sectional view of the hard diskdrive device of the second embodiment of the present invention.

[0020]FIG. 5 is a longitudinal sectional view of the hard disk drivedevice in accordance with the prior art apparatus.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0021] A preferred embodiment of a hard disk drive device in accordancewith the present invention will now be described in detail withreference to the attached drawings.

[0022] In the attached drawings, reference numeral 1 is added to a motorincluding a base 2, a flange 2 a formed around the periphery of thebase, a cylindrical sleeve 3 formed at the center of the base integrallytherewith, and a bearing means 4 rotatablly journaling a shaft 5.

[0023] Said bearing means 4 is for example of a double row bearingapparatus including an outer race 6 of sleeve form with which upper andlower rolling contact grooves 9 and 12 are provided on its innerperipheral surface, a stepped shaft 5 having a larger diameter portion 5a and reduced diameter portion 5 b, an inner race 10 having on its outerperipheral surface an outer rolling contact groove 11, and upper andlower rows of balls 7 a and 7 b. The balls 7 a of the upper row areinterposed between a rolling contact groove 8 formed directly on theouter peripheral surface of the larger diameter portion 5 a of the shaftand the upper rolling contact groove 9 of the outer race 6. The balls 7b of the lower row are interposed between the rolling contact groove 11of the inner race 10 fitted around the reduced diameter portion 5 b ofthe shaft 5 and the lower rolling contact groove 12 of the outer race.Further, a sealing plate 13 is mounted on the respective end of theouter race. The outer diameter of the larger diameter portion of theshaft 5 is same as that of the inner race 10. In this connection, theballs 7 a and 7 b are formed to have the same diameter.

[0024] The shaft 5 is securely fitted at its upper end 5 c into thecentral aperture 14 a of the rotor or hub 14. The hub has at its outerperiphery a flange 15 depending downwardly therefrom. A magnet 16 issecured on the inner peripheral surface of the flange 15 so as toopposed with the outer peripheral surface of the stator 17 mounted onthe outer peripheral surface of the sleeve 3. There are slight clearancebetween the magnet and the stator. The stator includes coils 18 forconducting current.

[0025] The hub 14 of the hard disk drive device of the present inventionis provided with an inner shoulder 19 of the diameter D₄ smaller thanthe outer diameter D₂ of the magnet 16. As can be appreciated, thediameter D₄ is substantially the same as the inner diameter of thecentral aperture 20 a of the magnetic disk 20. The disk is fitted aroundthe inner shoulder 19, and then clamped between the flat surface of theshoulder 19 and a disk restraining plate 21. The plate is adapted to besecured on the hub 14 by thread 21 a.

[0026] The hub 14 is also provided with an outer shoulder 22 of thedeiameter D₃ larger than the outer diameter D₄ of the inner shoulder 19and smaller than the outer diameter D₁ of the flange 15. The outershoulder provides a clearance S between the magnetic disk 20 and theflange 15. This structure allows the access of the magnetic head 23 forwriting and/or reading datum and the head arm 24 supporting the head 23of its distal end to the central portion of the lower surface of themagnetic disk. Further, the influence of the leakage of the magneticflax from the magnet 16 and/or stator 17 to be affected on the magneticdisk 20 and/or magnetic head 23 is reduced by the clearance S

[0027] The head positioning mechanism 25 for moving the magnetic head 23to the desired radial location on the magnetic disk and stopped thereonis illustrated diagrammatically in FIG. 1.

[0028] In the hard disk drive device of the present invention, the outerdiameter D₁ of the downwardly depending flange 15 is substantiallylarger than the outer diameter D₄ of the inner shoulder 19 and/or theinner diameter of the central aperture 20 a of the magnetic disk 20.Even though the magnetic disk 20 standardized in the size of the centralaperture 20 a is used, it is possible to enlarge the outer diameter ofthe downwardly depending flange 15, with no restraint from the innerdiameter of the central aperture 20 a of the magnetic disk 20.

[0029] In this structure, the outer diameter D₂ and the inner diameterof the magnet 16, the outer diameter and the inner diameter D₅ of thestator 17, and the outer diameter and the inner diameter of the sleeve 3are also enlarged, so that the bearing means 4 having a larger outerdiameter D₆ can be used. In other words, the bearing means of higherstrength can be used without reducing the radial thickness of the magnet16 of the radial length of the stator 17, i.e. without any loss ofmagnetic flax from the magnet and/or the stator. Consequently, thebearing means can be strengthened without interfering the performance ofthe motor.

[0030] Moreover, the outer diameter D₇ of the shaft 5 can also beenlarged to improve the impact resistance thereof. In the bearing meansof the above mentioned embodiment, the impact resistance of the shaft issubstantially improved, since the shaft 5 is one that includes a largerdiameter portion 5 a.

[0031] Although the base 2 and the sleeve 3 are formed integrally witheach other by using the same material in the above mentioned embodiment,these members can be formed separately, and although the shaft 5 and thehub 14 are separate members in the above mentioned embodiment, thesemembers can be made integrally with each other by using the samematerial.

[0032] Although the bearing means 4 is formed as the double row ballbearing, a pair of ball bearings can ba substituted therefor, andalthough the shaft 5 is formed as a stepped shaft, a straight shaft canbe substituted therefor. Further, any other bearing such as a fluidbearing or a pneumatic bearing can also be used.

[0033] Finally, although the motor of the above-mentioned embodiment isof the outer rotor type, the motor of inner rotor type can also besubstituted therefor.

[0034] The second embodiment of the hard disk drive device in accordancewith the present invention will be described with reference to FIG. 4.This embodiment is different from the above-mentioned first embodimentin the structure around the bearing means 26 journalling the hub 20. Inthe structure of this embodiment, an aperture 28 a of a shaft 28 isfitted on a boss 27 provided on the central portion of the base 2, and ahub or rotor 29 is journalled around the shaft through a bearing means26 interposed therebetween.

[0035] Said bearing means 26 includes an outer race 30 of sleeve formwith which upper and lower rolling contact grooves are provided on itsinner peripheral surface, the stepped shaft 28 having a larger diameterportion and a reduced diameter portion, an inner race 32 having on itsouter peripheral surface an outer rolling contact groove, and upper andlower balls 31 a and 31 b interposed between the outer race and theshaft or inner race. The upper balls 31 a are interposed between theinner race 32 and an upper rolling contact groove formed on the innerperipheral surface of the outer race 30. The lower balls 32 b areinterposed between the rolling contact groove formed directly on thesurface of the larger diameter shaft portion and the lower rollingcontact groove formed directly on the surface of inner peripheralsurface of the outer race 30. Further a sealing plate 33 is mounted onthe lower end of the outer race 30. The outer diameter of the largerdiameter portion of the shaft and that of the inner race 32 aresubstantially identical, so that the balls of substantially the samediameter are used as the balls 31 a and 31 b.

[0036] The outer race 30 of sleeve form is formed integrally with thehub 29 by using the same material, and the opening formed though thebearing means is closed by the lid plate 34.

[0037] The stator 17 is connected to the stator holder 35 formedintegrally with the base by using the same material.

[0038] In this embodiment, the hub 29 is also provided with inner andouter shoulders 19 and 22. The outer diameter D₁ of the downwardlydepending flange 15 is larger than the outer diameter D₄ of the innershoulder 19. The diameter D₄ is substantially the same as the innerdiameter of the central aperture 20 a of the magnetic disk 20. Eventhough the magnetic disk 20 standardized in the size of the centralaperture 20 a is used, it is possible to enlarge the outer diameter ofthe downwardly depending flange l5, with no restraint from the innerdiameter of the central aperture 20 a of the magnetic disk 20.

[0039] In this structure, the outer diameter D₂ and inner diameter ofthe magnet 16 confined within the boundary of the flange 15, and theouter diameter D_(g) and inner diameter of the stator 17 are alsoenlarged, so that the bearing means 26 having a larger outer diametercan be used. In other words, the bearing means of higher strength can beused without reducing the radial thickness of the magnet 16 of theradial length of the stator 17, i.e. without reducing the density of themagnetic flax from the magnet and/or the stator. Consequently, thebearing means can be strengthened without interfering the performance ofthe motor.

[0040] Moreover, the outer diameter D₇ of the shaft 28 can also beenlarged to improve the impact resistance thereof.

[0041] The effects and advantages of the present invention

[0042] The hard disk drive device in accordance with the presentinvention having a construction as mentioned above will providefollowing effects. It is possible to enlarge and strengthen the bearingmeans with no limitation by the inner diameter of the central apertureof the magnetic disk. In this connection, the impact resistance of thebearing means against damaging thereof by the concentration of stressdue to the impact of the hard disk drive device can be increasedsubstantially, and the lifetime of the bearing means can be extendedaccordingly.

[0043] Consequently, a hard disk drive device of mechanically higherreliability as well as long lifetime can be provided.

[0044] The high accuracy of rotation can be obtained by enlarging thesize of the boaring means, i.e. the possibility of decreasing of theaccuracy of rotation is reduced. The motor for driving the magnetic diskcan be rotated accurately in high speed, and the reduction of the noiseand vibration due to rotation.

[0045] The high accuracy of rotation will assure thc high packingdensity of the magnetic disk and the high capacity of memory for storingdatum.

[0046] Further, the diameter of the shaft can be enlarged in the largerbearing means. Thus, the vibration and the noise produced by resonancecan be eliminated.

[0047] The outer shoulder formed outwardly of the inner shoulder willprovide a clearance between the magnetic disk and the flange. Thisstructure allows the access of the magnetic head and the head arm intothe central portion of the lower surface of the magnetic disk, so thatthe memory surface of the magnetic disk can be utilized efficiently.Further, due to the clearance, the influence of the leakage of themagnetic flax from the magnet and/or the stator on the magnetic diskand/or the magnetic head is reduced or eliminated to increase thereliability of the hard disk drive device.

[0048] While particlular embodiments of the present invention have beenillustrated and described, it should be obvious to those skilled in theart that various changes and modifications can be made without departingfrom the spirit and scope of the invention.

What is claimed is:
 1. A hard disk drive device comprising a motorincluding; a rotor or hub having around outer periphery thereof adownwardly depending flange, said hub is journalled rotatablly on a baseby means of a bearing means, said hub is provided with a magnet on theinner peripheral surface of the downwardly depending flange, the hub isalso provided with an inner shoulder on the top thereof; and, a statorprovided on the base so as to opposed face to face with said magnet,said stator includes coils: and, a magnetic disk having a centralaperture to be fitted around the inner shoulder provided on the hub;wherein the outer diameter of the downwardly depending flange of saidhub is larger than the inner diameter of the central aperture of themagnetic disk, the outer diameter of said magnet surrounded by saiddownwardly depending flange is larger than the outer diameter of saidinner shoulder, and the inner diameter of the magnet as well as theouter and inner diameters of the stator are enlarged, and the outerdiameter of the bearing means is enlarged.
 2. The hard disk drive deviceaccording to claim 1, wherein the bearing means includes an outer raceof sleeve form mounted vertically on said base, a stopped shaft havingan upper enlarged diameter shaft portion and a lower reduced diametershaft portion, and an inner race fitted around the reduced diameterportion of the shaft, and upper and lower rows of balls, wherein saidouter race is provided on the inner peripheral surface thereof withupper and lower rolling contact grooves, said hub is fixedly secured tothe upper end of the shaft, balls of the upper row are interposedbetween a rolling contact groove formed directly on the outer peripheralsurface of the larger diameter portion of said shaft and the upperrolling contact groove of said outer race, and balls of the lower roware interposed between a rolling contact groove formed on the outerperipheral surface of the inner race and the lower rolling contactgroove of said outer race.
 3. The hard disk drive device according toclaim 2, wherein the outer diameter of the larger diameter portion ofsaid shaft and that of the inner race are substantially equal, so thatthe diameter of the balls of the upper row is substantially equal tothat of the balls of the lower row.
 4. The hard disk drive deviceaccording to claim 1, wherein the bearing means includes an outer raceof sleeve form integrally formed with said hub to depend downwardly fromthe central portion of said hub, a stepped shaft having a lower enlargeddiameter shaft portion and an upper reduced diameter shaft portion, andan inner race fitted around the reduced diameter portion of the shaft,and upper and lower rows of balls, wherein said outer race is providedon the inner peripheral surface thereof with upper and lower rollingcontact grooves, said shaft is mounted vertically on said base, theballs of the upper row are interposed between a rolling contact grooveformed on tho outer peripheral surface of the inner race and the upperrolling contact groove of said outer race, and the balls of the lowerrow are interposed between a rolling contact groove formed directly ontothe outer peripheral surface of the larger diameter portion of saidshaft and the lower rolling contact groove of said outer race.
 5. Thehard disk drive device according to claim 4, wherein the outer diameterof said larger diameter portion of said shaft is substantially equal tothat of the inner race, so that the diameter of the balls of the upperand lower rows are substantially identical with each other.
 6. A harddisk drive device comprising a motor including; a rotor or hub havingaround outer periphery thereof a downwardly depending flange, said hubis journalled a rotatablly on a base by means of a bearing means, saidhub is provided with a magnet on the inner peripheral surface of thedownwardly depending flange, the hub is also provided with an innershoulder on the top thereof; and, a stator provided on the base so as toopposed face to face with said magnet, said stator includes coils: and,a magnetic disk having a central aperture to be fitted around the innershoulder provided on the hub: wherein the outer diameter of thedownwardly depending flange of said hub is larger than the innerdiameter of the central aperture of the magnetic disk, the outerdiameter of said magnet surrounded by said downwardly depending flangeis larger than the outer diameter of said inner shoulder, the innerdiameter of the magnet as well as the outer and inner diameters of thestator are enlarged, and the outer diameter of the bearing means isenlarged, said hub also includes an outer shoulder larger in itsdiameter than that of the inner shoulder and smaller than that of thedownwardly depending flange to form a clearance allowing the access ofthe magnetic head into the space defined between the downwardlydepending flange and the magnetic disk.
 7. The hard disk drive deviceaccording to claim 6, wherein the bearing means includes an outer raceof sleeve form mounted vertically on said base, a stepped shaft havingan upper enlarged diameter shaft portion and a lower reduced diametershaft portion, and an inner race fitted around the reduced diameterportion of the shaft, and upper and lower rows of balls, wherein saidouter race is provided on the inner peripheral surface thereof withupper and lower rolling contact grooves, said hub is fixedly secured tothe upper end of the shaft, balls of the upper row are interposedbetween a rolling contact groove formed directly on the outer peripheralsurface of the larger diameter portion of said shaft and the upperrolling contact groove of said outer race, and balls of the lower roware interposed between a rolling contact groove formed on the outerperipheral surface of the inner race and the lower rolling contactgroove of said outer race.
 8. The hard disk drive device according toclaim 7, wherein the outer diameter of the larger diameter portion ofsaid shaft and that of the inner race are substantially equal, so thatthe diameter of the balls of the upper row is substantially equal tothat of the balls of the lower row.
 9. The hard disk drive deviceaccording to claim 6, wherein the bearing means includes an outer raceof sleeve form integrally formed with said hub to depend downwardly fromthe central portion of said hub, a stepped shaft having a lower enlargeddiameter shaft portion and an upper reduced diameter shaft portion, andan inner race fitted around the reduced diameter portion of the shaft,and upper and lower rows of balls, wherein said outer race is providedon the inner peripheral surface thereof with upper and lower rollingcontact grooves, said shaft is mounted vertically on said base, theballs of the upper row are interposed between a rolling contact grooveformed on the outer peripheral surface of the inner race and the upperrolling contact groove of said outer race, and the balls of the lowerrow are interposed between a rolling contact groove formed directly ontothe outer peripheral surface of the larger diameter portion of saidshaft and the lower rolling contact groove of said outer race.
 10. Thehard disk drive device according to claim 9, wherein the outer diameterof said larger diameter portion of said shaft is substantially equal tothat of the inner race, so that the diameter of the balls of the upperand lower rows are substantially identical with each other.